The investigators have been engaged in the study of surgical diseases using germfree and defined flora animals. We seek support for studies of three specific lesions: (1) Eck fistula encephalopathy; (2) stress ulcer; (3) burns. We have developed models of these lesions in germfree animals. We hope that further development will result in a clearer understanding of the role of the indigenous microflora in these abnormalities. Germfree Eck fistual dogs exhibit the biochemical abnormalities, behavioral and neurologic symptoms, and anatomic changes seen in the conventional animal with an Eck fistual. Traditional concepts of hepatic encephalopathy assign a major role to ammonia produced by bacterial degradation of dietary protein. If this is so, where does the ammonia come from in germfree dogs? What effect will Neomycin or Lactulose have on encephalopathy in germfree animals? What is the effect of specific amino acids on encephalopathy? Will changes in the dietary source of proteins alter encephalopathy in germfree and conventional dogs? Restraint of germfree animals produces ulcerations of the gastric mucosa significantly less severe than those observed in conventional animals. G-F animals are also protected from indomethacin induced ulcer. Elucidation of the reasons for these differences may produce new methods for the prevention of the highly lethal stress ulcer which appears so frequently in seriously ill patients. Can specific bacteria be implicated? Is endotoxin involved? What anatomic differences can be identified in G-F or conventional stress ulcers? The germfree rat with a 25% burn behaves in a manner strikingly different from conventionals. Eschar separation is markedly delayed. Burns of equal intensity produce a smaller injury in G-F animals. Explanations for these observations will be sought in an investigation of the G-F burned rat model. These models have proved workable and exciting. We hope over the next few years they will provide better insight into these three interesting lesions.